1. Field of the Invention
The present invention relates to a semiconductor chip, a semiconductor wafer, and a semiconductor device, in which a concave portion (including a penetration hole) is formed in a semiconductor substrate, by using a sandblast method, and a method of manufacturing the semiconductor device.
2. Description of the Related Art
For example, when a recording head of a thermal inkjet printer is manufactured, a driver circuit is formed on a semiconductor substrate such as a silicon substrate and a heater (heating resistor) material is laminated thereon. Further a cavity as an ink room for each pixel and an orifice nozzle as a discharge opening of ink are formed on the heater. Since the ink is supplied from the rear side surface of the silicon substrate, an ink supply hole (a penetration hole) which penetrates the silicon substrate is formed.
Generally, the above ink supply hole is formed from both side surfaces of the silicon substrate by using the sandblast method in view of a hole forming speed. In the sandblast method, as known well, a region except for a region to be dug is masked and then a particle with a small size, such as alumina, is blasted to a semiconductor device with a semiconductor wafer state at a predetermined rate. Thus, the silicon substrate and the structure formed thereon are mechanically removed.
Therefore, there is the following problem in the case of a semiconductor (silicon) device in which the concave portion (including the penetration hole) is necessarily formed in the silicon substrate by the sandblast method. That is, a defect such as a chip or a crack is easily caused in processing ends of the concave portion by chipping. The chipping is a phenomenon that, when silicon in a region in which the concave portion is formed is removed, not only silicon in a region in which sandblasting particles collide and but also silicon (removal is not desired) in a region outside of a circumferential portion of the concave portion are removed together.
An object of the present invention is to provide a semiconductor chip, a semiconductor wafer, and a semiconductor device, in which the problem based on the above related art is solved and a concave portion (including a penetration hole) is formed in a semiconductor substrate by a sandblast method, without causing a defect such as a chip or a crack in processing ends of the concave portion, and a method of manufacturing the semiconductor device.
In order to achieve the above object, according to the present invention, there is provided a method of manufacturing a semiconductor device in a semiconductor wafer in which a plurality of semiconductor chips are formed, comprising the steps of: forming a metal film on a semiconductor substrate in a region of a predetermined range in an inside and an outside of a circumferential portion except for at least a central portion and its vicinity of a region in that a concave portion of each of the semiconductor chips is to be formed; masking an entire surface of the semiconductor wafer including the metal film except for the region in that the concave portion of each of the semiconductor chips is to be formed; and forming the concave portion in each of the semiconductor chips formed on the semiconductor wafer by a sandblast method.
Here, a protective film for improving adhesion between the metal film and a material for masking is preferably formed on the metal film. In addition, a film thickness of the metal film is preferably in a range of 5 xcexcm to 0.05 xcexcm.
In addition, it is preferable that the metal film is formed on a front side surface of the semiconductor substrate and a formation of the concave portion is started from the front side surface of the semiconductor substrate. Alternatively, it is preferable that the metal film is formed on a rear side surface of the semiconductor substrate and a formation of the concave portion is started from the rear side surface of the semiconductor substrate. Alternatively, it is preferable that the metal films are formed on a front side surface and a rear side surface of the semiconductor substrate and a formation of the concave portion is started from the front side surface and the rear side surface of the semiconductor substrate.
Each of the semiconductor chips is preferably a recording head of a thermal inkjet printer.
Also, according to the present invention, there is provided a semiconductor device in a semiconductor wafer in which a plurality of semiconductor chips are formed, characterized in that a metal film is formed on a semiconductor substrate in a region of a predetermined range in an inside and an outside of a circumferential portion except for at least a central portion and its vicinity of a region in that a concave portion of each of the semiconductor chips is to be formed, an entire surface of the semiconductor wafer including the metal film is masked except for the region in that the concave portion of each of the semiconductor chips is to be formed, the concave portion is formed in each of the semiconductor chips formed on the semiconductor wafer by a sandblast method, and then, a subsequent semiconductor manufacturing process is continued with a state that at least a portion of the metal film is removed.
Also, according to the present invention, there is provided a semiconductor chip comprising: a semiconductor substrate in which at least one concave portion is formed; and a metal film which is formed on the semiconductor substrate in a region of a predetermined range in an outside of a circumferential portion of the concave portion, and in which an end surface of the circumferential portion of the concave portion is exposed.
Also, according to the present invention, there is provided a semiconductor wafer comprising: a plurality of semiconductor chips, in which each of the semiconductor chips includes, a semiconductor substrate in which at least one concave portion is formed, and a metal film which is formed on the semiconductor substrate in a region of a predetermined range in an outside of a circumferential portion of the concave portion, and in which an end surface of the circumferential portion of the concave portion is exposed.